The integration of different radio access networks, such as the integration of e.g. UTRANs (Universal Terrestrial Radio Access Network) and WLANs (Wireless Local Area Network), is currently of great interest for providing more flexible radio networks regarding e.g. coverage, capacity and services and thus for creating new/enhanced business opportunities.
FIG. 1 illustrates the basic architecture of a cellular radio network in form of a conventional UTRAN, connected to the Internet 180 and to a conventional WLAN. The UTRAN comprises a base station node B, 150, connected to a radio network controller, RNC, 130. The UTRAN is connected to the Internet, 180, through a SGSN (Serving GPRS Support Node) 120 and a GGSN (Gateway GPRS Support Node), 110, in a conventional manner. The WLAN in FIG. 1 is a conventional WLAN according to the IEEE 802 standard and normally comprises at least one radio Access Point, AP, 165, normally connected to an Access Point Controller, APC, 162. Now, the WLAN's APC is hereafter referred to as an M-L2S (Multicast-enabled Layer 2 Switch). Since the Ethernet (IEEE 802.3) protocol is used for most of the WLANs layer 2 protocols to communicate with fixed network infrastructure, an M-L2S is identical with an Ethernet switch. A dual mode UT (User Terminal) 140, having both UTRAN and WLAN capability, can establish a UTRAN radio connection through its first data port 141 with Base station Node B 150 and a WLAN radio connection through its second data port 142 with the AP 165 of the WLAN. The UTRAN and WLAN are in a conventional manner interconnected through the SGSN 120 or, as illustrated in FIG. 1, through the GGSN 110. In a conventional manner, the WLAN, i.e. APC, 162, may be directly connected to the GGSN, 110, as illustrated in FIG. 1, or be connected via an AR (Access Router) and/or an IP-network (not shown in FIG. 1).
A data communication session can be established between the UT 140 and a communicating party, such as a host/server or peer, connected to the Internet 180. The data communication session may e.g. in a conventional manner be realized by a PDP (Packet Data Protocol) context session between the UT, 140, and the GGSN, 110, over the UTRAN path, in accordance with the 3GPP standard for packet radio data services.
In case of a handover of a PDP context session from the UTRAN routing path to the WLAN routing path, a lot of signalling is needed and high delays are expected since the user data, i.e. downlink PDP packets, that have been sent to and cached in the corresponding UTRAN node. i.e. the RNC 130, but not yet transmitted to the user terminal UT, 140, must be forwarded back across the core network, i.e back to the GGSN, 110, to be routed further to the UT 140 via the APC 162 and AP, 165.
Another problem is that the cellular radio access network, i.e the RNC 130, in the network architecture illustrated in FIG. 1 has no access to the WLAN's RRM-(radio resource management) information, and the WLAN has no access to the cellular radio network's RRM information, hindering an efficient multi radio resource management of the entire integrated UTRAN-WLAN-network, which in turn decreases the capacity of the entire integrated UTRAN-WLAN-network.
More specifically, for the WLAN in FIG. 1, in case the WLAN requires authentication of the UT 140 before a data session can be set up over the WLAN path, the establishment of a security association between the UT 140 and AP 165, e.g. by applying a conventional standard EAP (Extensible Authentication Protocol) authentication in accordance with the IEEE 802.11i security specification, may pose a crucial issue regarding the caused interruption time, i.e. it may cause unacceptable packet delay/loss for real time applications such as voice and/or video, in case of a communication/data session handover e.g. from the UTRAN path to the WLAN path in FIG. 1.
There is a need to find methods and means allowing an efficient, flexible and versatile handover of communication sessions in integrated radio access networks comprising different types of radio access networks which exploit different technology standards regarding e.g. session management, mobility management, radio resource management, security management etc, such as an integrated network comprising a cellular radio networks, e.g. according to the UTRAN 3GPP standard, and a wireless data networks, e.g. according to the WLAN IEEE 802 standard, as illustrated in FIG. 1. General problems regarding efficient handover schemes for radio access networks relate e.g. to data loss minimization, interference suppression, packet delay minimization and to minimize network signaling.
More specifically, there is a need to find means and methods allowing efficient handover in integrated radio access networks for handovers involving different RNCs, such as when a communication session is routed over from one RNC to another.